The present invention relates to a new and distinct cultivar of Hydrangea macrophylla and will be referred to hereafter by its cultivar name, ‘H21-3’. ‘H21-3’ represents a new bigleaf hydrangea, a perennial shrub grown for landscape use.
‘H21-3’ was derived from an ongoing controlled breeding program directed by the Inventor that focuses on developing new cultivars of bigleaf hydrangeas with unique flower colors and double flowers. ‘H21-3’ arose from a cross made by the Inventor in Kyoto, Japan in May of 2008 between a Hydrangea macrophylla plants ‘Yamaajisai’ (not patented) as the female parent and ‘97 Pyra’ (not patented) as the male parent. ‘H21-3’ was selected as a single unique plant from amongst the resulting seedlings in May of 2010.
Asexual propagation of the new cultivar was first accomplished by stem cuttings by the Inventor in Kyoto, Japan in July of 2010. Asexual propagation by stem cuttings has determined that the characteristics of the new cultivar are stable and are reproduced true to type in successive generations.